1. Field of The Invention
The present invention relates generally to an arrangement for installation of a head up display. Specifically the invention relates to an arrangement for installing a head up display in an automotive vehicle.
2. Description of The Prior Art
It is known to install a so called `head up` display in an automotive vehicle so as to project instrument readings or the like on a portion of a windshield panel such that a driver may check the display readings without need of looking down. Examples of such head up displays have been described in Nissan Automotive Service Manual for model S13, May 1987, pg. 599 (FIG. 5) and Toyota Automotive Service Manuals for models E-JZS149 and E-UZS141 (FIG. 6).
Referring to FIG. 5, a positioning of a windshield panel 1 relative an installment panel 2 of one such conventional arrangement can be seen. A display unit 3 is installed within the installment panel 2 to project a display through an opening 2a provided in the installment panel 2. The display is projected through a finisher 4 mounted to cover the opening 2a. Within the display unit 3, a housing 5 containing a high luminance fluorescent light 6 and a mirror 7 are provided.
In operation, the fluorescent light 6 outputs display information, such as a speed indication via the mirror 7 to a reflective portion 1a provided on the windshield panel 1 to be reflected to a driver's side of the vehicle interior to be viewed along a line of sight `a`. The display unit 3 is connected with a meter 8, in this case a speedometer, for receiving speed data. The speedometer has a display portion 9 for direct viewing in addition to the head up display.
According to the conventional arrangement of FIG. 6, a meter 11 has a head up display projector 12 arranged therewithin, the output display (i.e a speed indication) is reflected by a first mirror 13 and a second mirror 15 installed in a head up display unit 14. The image reflected from the second mirror 15 is then reflected through a hologram lens 16 to a reflective portion 17 on a vehicle windshield to be displayed as a displayed image 18 along a drivers line of sight (arrow direction in FIG. 6).
However, the arrangements described above have various drawbacks. For example, in the arrangement of FIG. 5 servicing of the fluorescent light 6 can only be accomplished by removal of the head up display unit 3. Thus, the opening 2a must be made quite large in size. Also, in order to cover the opening 2a, the finisher 4 must also be large. In addition, after such servicing, it becomes necessary to readjust the alignment of the reflective elements with respect to the reflective portion 1a to assure proper image display.
In the arrangement of FIG. 6, since the image is projected through a plurality of reflective elements (i.e. the mirrors 13, 15) as well as a hologram lens and the reflective portion 17, a large space is needed for obtaining proper reflective characteristics. Also, a cost of the unit is increased due to the large number of components.
Therefore it has been required to provide a 30 head up display for a vehicle which is small in size and utilizes a minimum of reflective elements for reducing costs and conserving space.